Flowing granular materials are the basis of many industrial processes. Because of their complex physical properties, they place high demands on the simulation, that is to say the modelling and numerical solution. The difficulties in the modelling arise from the necessity to integrate physical effects like stagnation and a maximum packing density into a hydrodynamic model. The numerical difficulties arise from the complexity and non-linearity of a model of this type.

Picture 1

The Complex Fluids Group has developed such a model and demonstrated its industrial applicability in the scope of several successful projects. Different non-linear, finite volume methods were developed for the numerical solution. Modelling and numerical methods are implemented in the CoRheoGrain software – a module of the CoRheoS software platform. From the reading of arbitrary geometries to the visualisations, CoRheoGrain is able to cover the simulation
of granular flows.

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An important advantage of CoRheoGrain in comparison to particle-based methods like DEM is the treatment of the granular material as a continuum. This enables the simulation of both slow and fast granular processes with industrially-relevant material volumes and realistic particle sizes of different granulates and powders in the customary CFD context with similar computation times. The microscopic interaction of particles becomes part of the continuum modelling here. In addition, the parallelisability of CFD processes can be achieved very effectively and is intensively investigated. These results can be applied directly to the method in CoRheoGrain for the further reduction of simulation times.

In the past year the application field for CoRheoGrain was greatly expanded once again by the interaction of moving components with granular media. Building on the initial success of promising testing (Figure 1), an industrial project for the simulation of mixing machines with rapidly moving components was successfully completed.

In doing so, enhancements arose for the simulation of the flow behaviour in silos. Inserts are often used for the improvement or the control of the flow behaviour. For example, the CoRheoGrain software can play an important role in the optimisation of the type and position of such components. In Figure 2 a simple version of one such silo is shown with an insert.

This approach, as well as the complete parallelization and the more precise modelling of the behaviour of granulates on solid walls will continue to improve the usability and the quality of CoRheoGrain simulations in the coming year.